Showing papers by "Hany Hassanin published in 2015"
30 Jan 2015-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the as-fabricated strut size, morphology and internal porosity were investigated using optical microscopy, scanning electron microscopy (SEM) and X-ray microtomography (micro-CT) and correlated to the compressive properties of the structure.
Abstract: AlSi10Mg cellular lattice structures have been fabricated by selective laser melting (SLM) using a range of laser scanning speeds and powers. The as-fabricated strut size, morphology and internal porosity were investigated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray microtomography (micro-CT) and correlated to the compressive properties of the structure. Strut diameter was found to increase monotonically with laser power while the porosity was largest at intermediate powers. Laser scanning speed was found to thicken the struts only at slow rates while the porosity was largest at intermediate speeds. High speed imaging showed the melt pool to be larger at high laser powers. Further the melt pool shape was found to vary cyclically over time, steadily growing before becoming increasingly instable and irregularly shaped before abruptly falling in size due to splashing of molten materials and the process repeating. Upon compressive loading, lattice deformation was homogeneous prior to the peak stress before falling sharply due to the creation of a (one strut wide) shear band at around 45° to the compression axis. The specific yield strength expressed as the yield stress/(yield stress of the aluminium × relative density) is not independent of processing conditions, suggesting that further improvements in properties can be achieved by process optimisation. Lattice struts failed near nodes by a mixture of ductile and brittle fracture.
282 citations
TL;DR: In this article, the authors used selective laser melting (SLM) to produce tooling (a shell) that is filled with powder and subsequently consolidated via hot isostatic pressing (HIPing) so that the tooling, rather than being removed, becomes part of the sample.
31 citations
25 Jun 2015-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
5 citations
01 Jan 2015
TL;DR: In this paper, the soft lithography is used as a robust process for the fabrication of freestanding micro-ceramic components for micro-electromechanical systems applications.
Abstract: Ceramic materials have been fabricated using various forming processes for its great promise in applications where the operating conditions are harsh. However, there has been hardly research work invested to produce freestanding ceramic components for micro-electromechanical systems applications. This chapter discusses the soft lithography as a robust process for the fabrication of freestanding micro-ceramic components. The aim is to fill the technical gap in precision fabrication by developing a high-quality ceramic micro-fabrication approach suitable for mass production. The research can be divided into three main sections. In the first section, fabrication processes of high-precision hard and soft molds were studied and optimized. In the second section, different slurry systems to fill soft molds were evaluated. Finally, characterization of the sintered parts is included with the aim to find the proper composition and processing parameters.
2 citations